INFLUENCE OF ADDITIVES ON SELECTIVE NONCATALYTIC REDUCTION OF NO WITH NH3 IN CIRCULATING FLUIDIZED-BED BOILERS

The application of selective noncatalytic reduction of nitric oxide with ammonia in circulating fluidized bed boilers is investigated. Special attention is directed to the use of additives to the ammonia so that the efficiency of the NO reduction at lower temperatures can be increased. Tests under realistic conditions in a research boiler and reaction kinetic calculations show that the type of additives used did not improve the process. On the other hand, it is shown that ammonia injection as such, when employed before the cyclone of the boiler, effectively reduces the NO emission to a level of 20-60 ppm, without significant negative effects such as ammonia bypass and an increased CO emission.